Search-light, projector, and the like.



H. VIERTEL. SEARCH LIGHT, PROJECTOR, AND THE LIKE."

APPLICATION FILED KAY 25, 1907.

Patented Aug. 30,1910.

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. UNITED srarns PATENT OFFICE.

.- man, or cmanor'rmmune, cnmtmr lassmnoa 'ro ennmmma i SIEMENS & 00., 0] CHARLOTTENBUBG, NEAR BERLIN, GERMANY SEARCH-LIGHT, PROJECTOR, AND THE LIKE.

Specification Letterllatent. P tented Aug. 30, 1910.

To all whom it may concern:

Be it known that I, Hermit Vmnrnn, a subject of the German Emperor, resident of Charlottenburg,'near Berlin, Germany, have invented a certain new and useful Improvement in Search-Lights, Projectors, and the Like, of which the following is a. specifica U My present invention relates generally to search lights, projectors and the like, and

. more particularly to an electrode therefor,

It has been found in practice that numerous advantages are obtained by forming the cathode or negative electrode of arc lam s of certain types of substantially smaller iameter than the anode. Cathodes of this kind always burn away in the form of a slender point, whereas carbon electrodes known hitherto have always developed blunt or spherical ends. Arcing electrodes disclose aigrets of light emanating from the electrodes. If a very thin negative electrode and a thick positive electrode are used and the electrodes carry a strong current, only a negative aigret can be seen. In the type of lamp forming the subject matter of my present invention the are or aigret of light passes from the s ender point axially of the rod in the form of a more or less fine jet and its position hardly varies during the entire period of burnin The formation of theuniform and flat. Obviously such an e ect features.

is of great importance in projectors and the like. The utility of such electrodes for projectors is further enhanced by the fact that the thin cathode but slightly covers the erater, and therefore a much more favorable employment of the illuminating field of the.

crater is possible than when thicker cathodes are employed. A still further advantage is that due to theflatter formation of the erater the two electrodes may be separated by a greater distance, so that the area of the erater becomes all the more free from obstruction. The more uniform and flatter formation of the crater and the greater distance between the two electrodes, as well as the increased steadiness of the arc, cause the are .to' burn continuously still and perfectly noiselessly. But the thin cathode, as heretoforeemployed, had certain objectionable Decrease in the diameter of the cathode as a conductor resulted in a corresponding increase of its resistance, so that the current being e ual, the heatingo'f the cathode was ser1o y lncreased. It often happened that the cathode became red hot at considerable distance from the are which was obviously a great obstacle to the .employment of these electrodes. It is desirable however to have the electrode heated in this way a slight distance from the are, so

as to cause the electrode to always burn awa in a slender point.

T e primary object of my invention is to avoid the objectionable features in the employment of cathodes of a relativel smaller diameter and this object is accomp ished b the use of a tube, preferably carbon,'whic surrounds the cathode at some distance from the arc and which is so arranged that it carries a portion of the current and the carbon rod or'cathode can be readily rotated in the tube, and is also capable of axial movement therein.

Other objects and advantages of my invention wil be apparent from the description of an embodiment thereof which I have shown in the accompanying drawings by wsi'y of example.

11 said drawings. Figure 1 is an elevation of parts of an anode and cathode with my invention applied thereto, part being in section. Fi 2 is an elevation partly in section of t e anode and cathode with their respective operating mechanisms, the oathode being shown w1th my invention applied thereto, and Fig. 2 is a rear elevation showing{ the escapement hereinafter referred to.

eferring now more specifically to said drawings a indicates the carbon tube which surrounds the inner end of the thin. cathode b at a suitable distance from the are, 0 indicates the anode of larger diameter than cathode b and d in -F i 1 indicates the formation of the are. T e are d as clearly shown in Fig. '1 issues from the cathode b and strikes against the anode c in the form of a jet, formin a crater on the positive electrode. In or or to protect carbon tube a from the intense heat of the glowing end of the cathode b, I preferablyprovide a cap is of fireproof material such as magnesium which fits on to the end of the tube a and surrounds cathode b. In order to permit the rotation and feeding of the cathode without necessitating at the same time the movement of the tube a and cap 70, the tube may fit within a hollow piece 2' and be secured thereto by a set screw shown'in Fig. 2, the hollow piece 2' being suitably secured to a plate e. Were it not for the fireproof cap lc which protects the tube a, the latter would have to e fed with the cathode b to compensate for its consumption, and the advantage of the smaller diameter of the cathode would thus be defeated. With the construction as described, however, it is apparent that the necessity of movin tube a is avoided. Furthermore it shouId be pointed out that the use of tube a permits the employment of stronger current than was permissible heretofore with electrodes of corresponding dimensions.

In connection with the movement of the electrode in the carbon tube, however, there is the disadvantage that a fall of otential occurs between the movable rod an the carbon tube, due to the resistance offered to the current in its passage from the core to the tube. After some time this resistance has the effect of forming a very small arc and particles of the core pass over to the sides of the surrounding carbon tube. These are deposited on the interior sides of the tube in well known manner and cause the rod to adhere firmly in the carbon tube, thus preventing the feed of the cathode. Furthermore, it has been observed that when the cathode is horizontally arranged it becomes consumed more rapidly at its lower side than at the to on account of the risin heat. Consequent y the oint from whic the negative aigret of light passes moves higher and soon gets out of the axis of the displaceable core and thebrightly illuminatmg spot on the positive carbon follows after it and this moves away from the axis of the reflector of the projector which must, of course, be avoided.

In order to avoid the two defects above noted at the same time, I rovide means for slowly rotating the cath e. This rotation prevents the cathode from adhering to the tube and at the same time maintains the point of the cathode in central position, since the parts which have at first been consumed too much move to the to and vice versa. For this purpose and a so to-feed the cathode, I employ a regulatin device which simultaneously rotates and eeds inward the cathode thus compensating for the consumption. This re dating device may be fastened to the cat ode itself or to the carbon holder, or it may also be arranged outside the case of the element. I have shown in Fig. 2 a suitable form of special regulating mechanism for the cathode. On the plate e a spiral screw f is attached and surrounded by a. tube 1' mounted to revolve in a ball bearing socket 'w as clearl shown. The electrode 1; is arranged inside t e spiral screw f and carries at its rear end a socket or cap it provided with a pin t, the latter the tube 7. A toothed wheel 2 fastened on the outside of tube 1' is driven by the clockwork 'u and regulated for uniform operation by the escapement g. When the toothed wheel z rotates the tube 7', electrode 6 is, by

reason of the pin t, also rotated and since the pin 2. is positioned in the coils of the spiral screw f this rotation causes it to simultaneously feed'the cathode 1) forward, But the proper regulation of the cathode is not the only diflicult to be overcome, the fact that there is suc an unusual variance in the rapidity of consumption of the two electrodes respectively due to their differences in diameter makes it difficult to maintain the illuminatin crater in fixed position. .To overcome t is difiiculty in accordance with the present invention, the positive carbon is moved in well known manner under the control of the current or tension, whereas the thin negative electrode is fed forward uniformly by an independent mechanism as above described. The feeding movement of the clockwork u may be readily regulated so that it corresponds exactly with the diminution of the cathode due to its consumption.

By means of the cooperation of the cathode feed above described and the anode feed to be describedfithe former depending on time and the latter depending upon electrical considerations, great simplicity and certainty of regulation is obtained and simultaneously the advantage is also obtained that the mechanical resistances which are met with when the negative carbon is fed forward and rotated can have no influence on the re ulation, as they are easily overcome by t e clockwork 2:. Should the clockwork mechanism feed too fast the negative electrode projects farther from thefireproof cap and hence is more rapidly consumed, whereas should the clockwork feed too slowly the negative electrode is less exposed and hence more slowly consumed, so that any inequality of feed will be automatically self corrected.

Claims.

1. In an arc lamp of the typedescribed,

the combination with a positlve electrode and a negative electrode of substantially smaller'diameter' of an electrically conducting said negative electrode through said electricall conductive tube to cause the are We tube surrounding said negative electrode near the arc and adapted to carry a or-. tion of the arc current, and means for eed- Y end of said electrode to project beyond the protecting influence of said tube and carry the entire current.

2. In anarc lamp of the type described,

thecombi'nation with a' positive electrode and a negative electrode of substantially smaller diameter; of a fire-proof cap and an electrically conductive tube surrounding said negative electrode near the arc, said tube adapted to, carry aportion of the are current, and means for feeding said negative electrode through said electrically conductivc tube and fire-proof cap to cause the arc end of said electrode to project beyond the protecting influence of said tube and cap and carry the entire current.

3. In an arc lamp of the type described the combination with a positive electrode, and a negative electrode of substantially smaller diameter, of an electrically conductive tube surrounding said negative electrode near the arc, and means for rotating said negative electrode within said tube and causing it to project beyond said tube.

4. In an arc lamp of the type described,

the combination with a positive electrode,

and a negative electrodev of substantially smaller diameter; of an electrically conductive tube and fire-proof cap surrounding said negative electrode near the arc, and means for rotating said negative electrode within said tube and cap and causing it to project beyond said tube and cap.

5. In an arc lamp of the type described, the combination with a positive electrode, means for controlling the same, and a negative electrode of substantially smaller diameter; of an electrically conducting tube surrounding said negative electrode near the arc, but adapted to permit movement of said negative electrode within it, and clockwork controlled means for rotating and simultaneously feeding forward said negative electrode independently of said-tube so that a portion of said negative electrode projects beyond said tube.

6. In an arc lam electrically controlled mechanism for controlling the same, and a negative'electrode of substantially smaller diameter/than the positive electrode; of an electrically conducting tube and fire proof cap surrounding said negative electrode near the arc, but

adapted to permit movement of the negative electrode within it, and means driven by clockwork inde endently of said electrically controlled mec anism for rotatin multaneously feeding forward sai negative electrode inde endently of said tube and fire proof cap so t at a portion of said negative.

of the type described, the combination with a positive electrode,

and sielectrode projects beyond said tube and fire proof cap.

7. In an arc lamp of the type described, the combination with a frame, a positive electrode mechanism on said frame for controlling said electrode and a negative elec-' .trode of substantially smaller diameter than said positive electrode; of a holder on said frame, a carbon tube in said holder surrounding said negative electrode near the arc, but adapted to permit movement of the negative electrode within it, a screw attached to said frame surrounding the outer end of said negative electrode, a second tube having a longitudinal slot rotatably mounted on said frame, and inclosing said screw, a socket on the outer end of said negative electrode, a pin on said socket slidably resting in said slot in said second tube, and clockwork means for rotating said second tube at a uniform speed whereby said negative electrode is rotated and fed forward independently of said carbon tube.

8. In an arc lamp of the type described, the combination with a frame, a positive electrode, electrically controlled mechanism on said frame for controlling said electrode, and a ne ative electrode of substantially smaller dlameter than said positive electrode; of a carbon tube in said holder surrounding said negative electrode near the arc, butadapted to permit said negative electrode to'move within it, a fireproof cap loosely surrounding said negative electrode on the end of said tube adjacent to the arc, a screw attached to said frame and surrounding said negative electrode, a second tube having a longitudinal slot rotatably mounted on said frame and inclosing said screw, a socket on the outer end of said negative electrode, a pin on said socket slidably resting in said slot in said tube, and clockwork mechanism for rotatin said second tube at a uniform speed lndependently of said electrically controlled mechanism, whereby said ne ative electrode is rotated and simultaneous y fed forward at a unifogm speed independently of said carbon tu e.

In testimony whereof, I have signed my name to this specification in the presence of the two subscrlbi-n witnesses.

H RMANN VIERT'EL.

Witnesses:

HENRY HAsrER, WOLDEMAR HAUPT. 

